<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT	MIT License
 * @link    https://codeigniter.com
 * @since    Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Typography Class
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Helpers
 * @author        EllisLab Dev Team
 * @link        https://codeigniter.com/user_guide/libraries/typography.html
 */
class CI_Typography
{

    /**
     * Block level elements that should not be wrapped inside <p> tags
     *
     * @var string
     */
    public $block_elements = 'address|blockquote|div|dl|fieldset|form|h\d|hr|noscript|object|ol|p|pre|script|table|ul';

    /**
     * Elements that should not have <p> and <br /> tags within them.
     *
     * @var string
     */
    public $skip_elements = 'p|pre|ol|ul|dl|object|table|h\d';

    /**
     * Tags we want the parser to completely ignore when splitting the string.
     *
     * @var string
     */
    public $inline_elements = 'a|abbr|acronym|b|bdo|big|br|button|cite|code|del|dfn|em|i|img|ins|input|label|map|kbd|q|samp|select|small|span|strong|sub|sup|textarea|tt|var';

    /**
     * array of block level elements that require inner content to be within another block level element
     *
     * @var array
     */
    public $inner_block_required = array('blockquote');

    /**
     * the last block element parsed
     *
     * @var string
     */
    public $last_block_element = '';

    /**
     * whether or not to protect quotes within { curly braces }
     *
     * @var bool
     */
    public $protect_braced_quotes = FALSE;

    /**
     * Auto Typography
     *
     * This function converts text, making it typographically correct:
     *    - Converts double spaces into paragraphs.
     *    - Converts single line breaks into <br /> tags
     *    - Converts single and double quotes into correctly facing curly quote entities.
     *    - Converts three dots into ellipsis.
     *    - Converts double dashes into em-dashes.
     *  - Converts two spaces into entities
     *
     * @param    string
     * @param    bool    whether to reduce more then two consecutive newlines to two
     * @return    string
     */
    public function auto_typography($str, $reduce_linebreaks = FALSE)
    {
        if ($str === '') {
            return '';
        }

        // Standardize Newlines to make matching easier
        if (strpos($str, "\r") !== FALSE) {
            $str = str_replace(array("\r\n", "\r"), "\n", $str);
        }

        // Reduce line breaks.  If there are more than two consecutive linebreaks
        // we'll compress them down to a maximum of two since there's no benefit to more.
        if ($reduce_linebreaks === TRUE) {
            $str = preg_replace("/\n\n+/", "\n\n", $str);
        }

        // HTML comment tags don't conform to patterns of normal tags, so pull them out separately, only if needed
        $html_comments = array();
        if (strpos($str, '<!--') !== FALSE && preg_match_all('#(<!\-\-.*?\-\->)#s', $str, $matches)) {
            for ($i = 0, $total = count($matches[0]); $i < $total; $i++) {
                $html_comments[] = $matches[0][$i];
                $str = str_replace($matches[0][$i], '{@HC' . $i . '}', $str);
            }
        }

        // match and yank <pre> tags if they exist.  It's cheaper to do this separately since most content will
        // not contain <pre> tags, and it keeps the PCRE patterns below simpler and faster
        if (strpos($str, '<pre') !== FALSE) {
            $str = preg_replace_callback('#<pre.*?>.*?</pre>#si', array($this, '_protect_characters'), $str);
        }

        // Convert quotes within tags to temporary markers.
        $str = preg_replace_callback('#<.+?>#si', array($this, '_protect_characters'), $str);

        // Do the same with braces if necessary
        if ($this->protect_braced_quotes === TRUE) {
            $str = preg_replace_callback('#\{.+?\}#si', array($this, '_protect_characters'), $str);
        }

        // Convert "ignore" tags to temporary marker.  The parser splits out the string at every tag
        // it encounters.  Certain inline tags, like image tags, links, span tags, etc. will be
        // adversely affected if they are split out so we'll convert the opening bracket < temporarily to: {@TAG}
        $str = preg_replace('#<(/*)(' . $this->inline_elements . ')([ >])#i', '{@TAG}\\1\\2\\3', $str);

        /* Split the string at every tag. This expression creates an array with this prototype:
         *
         *	[array]
         *	{
         *		[0] = <opening tag>
         *		[1] = Content...
         *		[2] = <closing tag>
         *		Etc...
         *	}
         */
        $chunks = preg_split('/(<(?:[^<>]+(?:"[^"]*"|\'[^\']*\')?)+>)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY);

        // Build our finalized string.  We cycle through the array, skipping tags, and processing the contained text
        $str = '';
        $process = TRUE;

        for ($i = 0, $c = count($chunks) - 1; $i <= $c; $i++) {
            // Are we dealing with a tag? If so, we'll skip the processing for this cycle.
            // Well also set the "process" flag which allows us to skip <pre> tags and a few other things.
            if (preg_match('#<(/*)(' . $this->block_elements . ').*?>#', $chunks[$i], $match)) {
                if (preg_match('#' . $this->skip_elements . '#', $match[2])) {
                    $process = ($match[1] === '/');
                }

                if ($match[1] === '') {
                    $this->last_block_element = $match[2];
                }

                $str .= $chunks[$i];
                continue;
            }

            if ($process === FALSE) {
                $str .= $chunks[$i];
                continue;
            }

            //  Force a newline to make sure end tags get processed by _format_newlines()
            if ($i === $c) {
                $chunks[$i] .= "\n";
            }

            //  Convert Newlines into <p> and <br /> tags
            $str .= $this->_format_newlines($chunks[$i]);
        }

        // No opening block level tag? Add it if needed.
        if (!preg_match('/^\s*<(?:' . $this->block_elements . ')/i', $str)) {
            $str = preg_replace('/^(.*?)<(' . $this->block_elements . ')/i', '<p>$1</p><$2', $str);
        }

        // Convert quotes, elipsis, em-dashes, non-breaking spaces, and ampersands
        $str = $this->format_characters($str);

        // restore HTML comments
        for ($i = 0, $total = count($html_comments); $i < $total; $i++) {
            // remove surrounding paragraph tags, but only if there's an opening paragraph tag
            // otherwise HTML comments at the ends of paragraphs will have the closing tag removed
            // if '<p>{@HC1}' then replace <p>{@HC1}</p> with the comment, else replace only {@HC1} with the comment
            $str = preg_replace('#(?(?=<p>\{@HC' . $i . '\})<p>\{@HC' . $i . '\}(\s*</p>)|\{@HC' . $i . '\})#s', $html_comments[$i], $str);
        }

        // Final clean up
        $table = array(

            // If the user submitted their own paragraph tags within the text
            // we will retain them instead of using our tags.
            '/(<p[^>*?]>)<p>/' => '$1', // <?php BBEdit syntax coloring bug fix

            // Reduce multiple instances of opening/closing paragraph tags to a single one
            '#(</p>)+#' => '</p>',
            '/(<p>\W*<p>)+/' => '<p>',

            // Clean up stray paragraph tags that appear before block level elements
            '#<p></p><(' . $this->block_elements . ')#' => '<$1',

            // Clean up stray non-breaking spaces preceeding block elements
            '#(&nbsp;\s*)+<(' . $this->block_elements . ')#' => '  <$2',

            // Replace the temporary markers we added earlier
            '/\{@TAG\}/' => '<',
            '/\{@DQ\}/' => '"',
            '/\{@SQ\}/' => "'",
            '/\{@DD\}/' => '--',
            '/\{@NBS\}/' => '  ',

            // An unintended consequence of the _format_newlines function is that
            // some of the newlines get truncated, resulting in <p> tags
            // starting immediately after <block> tags on the same line.
            // This forces a newline after such occurrences, which looks much nicer.
            "/><p>\n/" => ">\n<p>",

            // Similarly, there might be cases where a closing </block> will follow
            // a closing </p> tag, so we'll correct it by adding a newline in between
            '#</p></#' => "</p>\n</"
        );

        // Do we need to reduce empty lines?
        if ($reduce_linebreaks === TRUE) {
            $table['#<p>\n*</p>#'] = '';
        } else {
            // If we have empty paragraph tags we add a non-breaking space
            // otherwise most browsers won't treat them as true paragraphs
            $table['#<p></p>#'] = '<p>&nbsp;</p>';
        }

        return preg_replace(array_keys($table), $table, $str);

    }

    // --------------------------------------------------------------------

    /**
     * Format Characters
     *
     * This function mainly converts double and single quotes
     * to curly entities, but it also converts em-dashes,
     * double spaces, and ampersands
     *
     * @param    string
     * @return    string
     */
    public function format_characters($str)
    {
        static $table;

        if (!isset($table)) {
            $table = array(
                // nested smart quotes, opening and closing
                // note that rules for grammar (English) allow only for two levels deep
                // and that single quotes are _supposed_ to always be on the outside
                // but we'll accommodate both
                // Note that in all cases, whitespace is the primary determining factor
                // on which direction to curl, with non-word characters like punctuation
                // being a secondary factor only after whitespace is addressed.
                '/\'"(\s|$)/' => '&#8217;&#8221;$1',
                '/(^|\s|<p>)\'"/' => '$1&#8216;&#8220;',
                '/\'"(\W)/' => '&#8217;&#8221;$1',
                '/(\W)\'"/' => '$1&#8216;&#8220;',
                '/"\'(\s|$)/' => '&#8221;&#8217;$1',
                '/(^|\s|<p>)"\'/' => '$1&#8220;&#8216;',
                '/"\'(\W)/' => '&#8221;&#8217;$1',
                '/(\W)"\'/' => '$1&#8220;&#8216;',

                // single quote smart quotes
                '/\'(\s|$)/' => '&#8217;$1',
                '/(^|\s|<p>)\'/' => '$1&#8216;',
                '/\'(\W)/' => '&#8217;$1',
                '/(\W)\'/' => '$1&#8216;',

                // double quote smart quotes
                '/"(\s|$)/' => '&#8221;$1',
                '/(^|\s|<p>)"/' => '$1&#8220;',
                '/"(\W)/' => '&#8221;$1',
                '/(\W)"/' => '$1&#8220;',

                // apostrophes
                "/(\w)'(\w)/" => '$1&#8217;$2',

                // Em dash and ellipses dots
                '/\s?\-\-\s?/' => '&#8212;',
                '/(\w)\.{3}/' => '$1&#8230;',

                // double space after sentences
                '/(\W)  /' => '$1&nbsp; ',

                // ampersands, if not a character entity
                '/&(?!#?[a-zA-Z0-9]{2,};)/' => '&amp;'
            );
        }

        return preg_replace(array_keys($table), $table, $str);
    }

    // --------------------------------------------------------------------

    /**
     * Format Newlines
     *
     * Converts newline characters into either <p> tags or <br />
     *
     * @param    string
     * @return    string
     */
    protected function _format_newlines($str)
    {
        if ($str === '' OR (strpos($str, "\n") === FALSE && !in_array($this->last_block_element, $this->inner_block_required))) {
            return $str;
        }

        // Convert two consecutive newlines to paragraphs
        $str = str_replace("\n\n", "</p>\n\n<p>", $str);

        // Convert single spaces to <br /> tags
        $str = preg_replace("/([^\n])(\n)([^\n])/", '\\1<br />\\2\\3', $str);

        // Wrap the whole enchilada in enclosing paragraphs
        if ($str !== "\n") {
            // We trim off the right-side new line so that the closing </p> tag
            // will be positioned immediately following the string, matching
            // the behavior of the opening <p> tag
            $str = '<p>' . rtrim($str) . '</p>';
        }

        // Remove empty paragraphs if they are on the first line, as this
        // is a potential unintended consequence of the previous code
        return preg_replace('/<p><\/p>(.*)/', '\\1', $str, 1);
    }

    // ------------------------------------------------------------------------

    /**
     * Protect Characters
     *
     * Protects special characters from being formatted later
     * We don't want quotes converted within tags so we'll temporarily convert them to {@DQ} and {@SQ}
     * and we don't want double dashes converted to emdash entities, so they are marked with {@DD}
     * likewise double spaces are converted to {@NBS} to prevent entity conversion
     *
     * @param    array
     * @return    string
     */
    protected function _protect_characters($match)
    {
        return str_replace(array("'", '"', '--', '  '), array('{@SQ}', '{@DQ}', '{@DD}', '{@NBS}'), $match[0]);
    }

    // --------------------------------------------------------------------

    /**
     * Convert newlines to HTML line breaks except within PRE tags
     *
     * @param    string
     * @return    string
     */
    public function nl2br_except_pre($str)
    {
        $newstr = '';
        for ($ex = explode('pre>', $str), $ct = count($ex), $i = 0; $i < $ct; $i++) {
            $newstr .= (($i % 2) === 0) ? nl2br($ex[$i]) : $ex[$i];
            if ($ct - 1 !== $i) {
                $newstr .= 'pre>';
            }
        }

        return $newstr;
    }

}
